Preparation of TiO₂–(B) by microemulsion mediated hydrothermal method: effect of the precursor and its electrochemical performance

Synthesis of TiO₂–(B) bronze was carried out by hydrothermal method using different precursors: (a) commercial anatase, (b) amorphous TiO₂ prepared by O/W microemulsion method and (c) oil-in-water (O/W) microemulsion with freshly prepared amorphous TiO₂. It is important to highlight this is the first report of the preparation of TiO₂–(B) using an O/W microemulsion as a precursor. The effect of precursor type on the resulting TiO₂ nanostructures, namely, their structural and morphological features were studied using X-ray diffraction, thermal analysis (TGA–DTA), Brunauer–Emmett–Teller, Raman spectroscopy and scanning electron microscopy (SEM–EDX). From commercial anatase powder, amorphous TiO₂ ME and O/W microemulsion ME238 (NaOH/TiO₂ molar ratio 238), biphasic nanoribbons were obtained: TiO₂–(B) (88–92%) and anatase (8–12%). While from the O/W microemulsion ME30 (NaOH/TiO₂ molar ratio 30) only anatase phase was obtained. The material with higher TiO₂–(B) phase content, showed an increase in its reversible capacity, thus the crystalline nature of the precursor as well as the textural properties contribute to the electrode performance. Materials synthesized from commercial anatase and amorphous TiO₂ ME exhibited similar charge retention (86–87%) despite the slight difference in reversible capacity, 210 and 180 mAh/g, respectively. It is noticed that TiO₂–(B)–AME (prepared from amorphous TiO₂ ME) exhibited the lowest capacity loss, e.g. the highest reversibility.